1. Field of the Invention
The products of this invention are adhesive products containing (a) an aminoalkyltrialkoxysilane, (b) a fine particle size polyvinyl chloride powder and/or (c) an amorphous hydrophobic silicic acid and (d) organic solvents. The adhesive products are employed for attaching cover layers of all types of cellular and non-cellular polyurethanes.
2. Description of the Prior Art
A prerequisite for attaching solid cover layers of identical or other optionally fiber-reinforced plastics, wood or metal to foamed plastics is sufficient adhesion of the foamed plastic to the cover layers. For sandwich constructions, for instance, the adhesion of the foamed plastic to the cover layer must be greater than the internal stability of the foamed plastic in order to avoid lifting of the cover layer as a result of buckling or bending [kinking] of the overall construction.
In order to improve the adhesiveness of polyurethane foams, it has been suggested to roughen the cover layer, for instance by sanding or sand blasting, and to cover this layer with a prime coat with a reaction accelerator such as a tertiary amine or metal salt for the foaming process. Another solution is priming the cover layer with adhesive based on polyurethane polyester resin, oxide resin or nitrile or rubber. The improved adhesion achieved with this process, however, is insufficient for many areas of application.
It is further known that the combination of organic resins such as epoxide-, unsaturated polyester-, phenol-, melamine resins and polymers such as styrene-, butadiene-, styrene-acrylonitrile polymers, polyamide, polypropylene and polyesters with hydrophilic mineral fibers can be improved by traces of reactive silanes as cross-linking agents. On the other hand, the use of silanes as adhesives for polyurethane is not mentioned.